Virtually no part of the world has remained untouched by HIV. Click on the map to read about how the virus has hit each region according to the United Nations Programme on Aids (UNAids) and World Health Organization (WHO).

SUB-SAHARAN AFRICA

2005 REGIONAL FIGURES

People with HIV: 25.8m

% of world's HIV cases: 64%

New cases: 3.2m

Aids deaths: 2.4m

More than 60% of all people with HIV live in Sub-Saharan Africa. Despite falls in adult HIV prevalence apparently under way in Kenya, Uganda and Zimbabwe, there is little evidence of declining epidemics in this region as a whole. In fact, prevalence levels remain "exceptionally" high and might not yet have reached their peak in several countries.

There is also particular concern at the way the virus affects women in this region, who are disproportionately affected by HIV while remaining poorly informed.

Low national HIV infection levels in Asia mask the fact that, because of large populations, sizeable numbers of people are living with HIV. Serious Aids epidemics in the region are fuelled by risky behaviour, often involving more than one form, and often related to drug-use and unprotected sex

However, there are concerns that many of the prevention strategies do not take into account this combination of risk-taking, even in those countries where the spread of HIV has so far been contained. One positive among the generally worsening international situation has been a fall in HIV incidence among sex workers and their clients in Thailand and Cambodia.

In North America and western Europe, the number of people living with HIV has continued to grow, although the number of Aids deaths remains comparatively low thanks to the wide availability of antiretroviral therapy.

Although sex between men and, in a minority of countries, injecting drug use remain important routes for HIV transmission, unprotected heterosexual intercourse is playing an increasingly significant role. There are concerns that in several countries prevention efforts are lagging behind this shifting pattern of HIV transmission.

Mainly because of their large populations, Argentina, Brazil and Colombia have seen the largest HIV epidemics in the region, with Brazil alone accounting for more than one third of the people living with HIV in Latin America.

The highest levels of HIV prevalence are found in the smaller countries of Belize, Guatemala and Honduras. No single factor is fuelling the region's epidemics, but a combination of unsafe sex (between men, and men and women) plus injecting drug use are primarily to blame.

In nearly all Latin American countries, according to recent studies reported by UNAids and the WHO, the highest levels of HIV infection are found among men who have sex with men and the second-highest among female sex workers.

The epidemics in this region are continuing to grow - the numbers infected have increased almost twentyfold in less than a decade - affecting ever-larger parts of societies. Between 2003 and 2005 the number killed by Aids almost doubled.

The infected population is predominantly young, with increasing numbers of women being affected, many acquiring HIV from male partners who became infected when injecting drugs. The bulk of cases are in the Russian Federation - which has the biggest Aids epidemic in Europe - and Ukraine.

Among Australia, New Zealand and the Pacific islands, only the two small island nations of Niue and Tokelau have not yet reported any HIV infections. Australia, with the oldest HIV epidemic in the region, saw declining infections between 1995 and 2000 but they have edged up again recently. Although spread primarily by sex between men, a rise in heterosexual infections has led to an increase in the number of women with HIV.

The number of HIV infections in New Zealand is much smaller than Australia's. The route of infection is similarly dominated by sex between men, with most infections picked up abroad. Incidences on other Pacific islands remains low, but continuing high levels of sexually transmitted disease have raised concerns that the conditions for an epidemic remain.

Once known as a region with relatively low levels of HIV, its advance is continuing, although sometimes poor availability of information does disrupt efforts to build-up a comprehensive picture.

There is evidence of increasing infections in countries such as Algeria, Libya, Morocco and Somalia. The main route of transmission is unprotected sexual contact, although injecting drug use is becoming more significant and is the primary route in both Libya and Iran. The prevalence of HIV in all populations is low, except for Sudan where despite recently intensified prevention efforts, HIV knowledge remains generally poor.

Aids is the leading cause of death among 15 to 44-year-olds in the Caribbean, although national HIV prevalence varies from as much as 3% in Haiti to less than 0.2% in Cuba. There are concerns about inadequate information gathering in the region, as well as the infrequent acknowledgement of the role played by sex between men, which is widely stigmatised. The main driver of the region's epidemics is, however, heterosexual intercourse, with commercial sex a prominent factor.

However, there is some optimism surrounding recent developments in countries such as the Dominican Republic, Barbados and Haiti, where HIV infection rates have declined in some areas. Changes in sexual behaviour are cited as one possible explanation.